Type E and EP Filters for Face Masks: Complete Guide to Respiratory Protection

Introduction

Type E and EP filters are essential Personal Protective Equipment (PPE) for respiratory protection against acid gases, harmful vapors, and dangerous dusts. Used with face masks for respiratory protection, they play a key role in workplace safety across high-risk industries.

When combined with particle filters (P), type E filters, provide complete protection against both gases and particulates, making them indispensable in critical industrial environments.

In this guide, we explain what Type E and EP filters are, which toxic substances they protect against — with a focus on sulfur dioxide (SO₂) and sulfur trioxide/sulfuric acid (SO₃/H₂SO₄) --, where they are used, and the main regulations that govern them.

 

What Are Type E and E P Filters?

Type Type E filters (yellow label) and Type EP filters (yellow + white label) are protective filters for face masks, designed for use with half masks and full-face masks..

1. Type E filters → rotect against acid gases and vapors, particularly sulfur dioxide (SO₂) and hydrochloric acid (HCl).
2. Type EP filters → are combined filters that provide protection against acid gases (E) and particle filtration (P1, P2, P3), defending against aerosols, mists, and dusts.

Thanks to specific adsorbent materials, these filters are the first line of defense against highly corrosive chemical contaminants such as SO₂, SO₃, and H₂SO₄.

Classes and markings:

1. Letter E = acid gas protection.
2. Numbers (1/2/3) = filter capacity (the higher the number, the greater the protection and duration).
3. La sigla P1/P2/P3 = particle filtration efficiency (P3 = maximum efficiency).

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Toxic Substances requiring Type E and E P Filters

Using Type E filters is recommended when working with chemical contaminants such as:

1. Formic acid → Corrosive liquid with a pungent odor, used in agriculture and chemical industries. Causes burns, respiratory irritation, and eye damage.
2. Sulfur dioxide (SO₂) → Colorless gas with a sharp odor, by-product of coal and sulfur combustion. Toxic to the respiratory system, irritant to eyes and mucous membranes.

Using Type EP filters is recommended when working with chemical contaminants such as:

1. Acetic acid → Diluted form is vinegar, but at high concentrations it is corrosive and irritating.
2. Hydrobromic acid → Extremely corrosive, causes severe burns and respiratory damage.
3. Acido cloridrico (HCl) → Liquido corrosivo e fumante, ampiamente usato nell’industria. A contatto provoca ustioni cutanee, lesioni oculari e irritazioni polmonari.
4. Hydrofluoric acid (HF) → Highly toxic, penetrates deep tissues and can be fatal.
5. Nitric acid (HNO₃) → Corrosive liquid used in fertilizers and explosives.
6. Sulfur trioxide (SO₃) → Highly reactive, forms sulfuric acid on contact with moisture.
7. Oleum → Mixture of sulfuric acid and sulfur trioxide, strongly corrosive and dangerous.

Focus on SO₂ and SO₃/H₂SO₄ (Oleum):

1. Sulfur dioxide (SO₂) is produced by combustion of sulfur-containing materials (coal plants, refineries, chemical plants).
   It irritates airways, causing coughing, wheezing, bronchospasms, and in severe cases pulmonary edema.
2. Sulfur trioxide (SO₃) reacts with humidity to form sulfuric acid (H₂SO₄) highly corrosive aerosols that cause severe respiratory and eye injuries, and penetrate deep into the lungs

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Recommended Work Environments

Type E and EP filters are recommended in many workplace:

1. Refineries, petrochemical plants, and oil & gas industries (desulfurization, SO₂ emissions).
2. Chemical and pharmaceutical industries (acid production and processing).
   
3. Fertilizer production and paper mills.
4. Metal treatment, industrial painting, and pickling operations where acid gases and aerosols may develop.
5. Power plants and combustion facilities.

Where acid gases and particulates are present simultaneously, combined E + P3 filters on respiratory protective masks are the safest choice.

 

Standards and Markings (Gas and Combined Filters)

To ensure maximum workplace safety, E and EP filters must comply with European standards:

1. EN 14387 defines requirements, testing, and markings for gas and combined filters(types A, B, E, K, etc. and classes 1–3).
2. EN 143 defines standards for particle filters (P1, P2, P3); P3 is the highest efficiency.
   
3. Combined filters show composite markings (e.g. E2P3 R or A2B2E2K2-P3 R). Yellow color = E filters.
4. Regulation (EU) 2016/425 defines requirements for PPE design and certification (including RPE).
   In Italy, guidelines UNI EN 529 / UNI 11719 support correct selection, usage, and fit testing.

All filters must carry CE marking, and clear usage/limitations instructions.

 

Conclusions

Type E and EP filters are indispensable respiratory protection devices for workplaces where acid gases and corrosive aerosols sulfur dioxide (SO₂) and sulfur trioxide/sulfuric acid (SO₃/H₂SO₄) are present..

Proper risk assessment, the right class choice (E1/E2/E3, P3 when needed), compliance with EN standards and regular fit testing are mandatory to ensure workplace safety.

Discover our full range of Type E and EP filters with universal connection, compatible with the main face masks for respiratory protection.

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